fix: no module named 'packaging.metadata'

Refs: python-poetry/poetry#9029

docker/Dockerfile.airflow.simple

@@ -19,7 +19,7 @@ COPY poetry.toml pyproject.toml /opt/airflow/zetsubou-venv/
 RUN chmod 755 /opt/airflow/zetsubou-venv/
 
 RUN pip install --upgrade pip \
-    && pip install --root-user-action=ignore --no-cache-dir poetry pydantic \
+    && pip install --root-user-action=ignore --no-cache-dir "poetry==1.7.1" pydantic \
     && pip install --root-user-action=ignore --no-cache-dir "apache-airflow[celery]==2.6.2" --constraint "https://raw.githubusercontent.com/apache/airflow/constraints-2.6.2/constraints-3.7.txt"
 
 WORKDIR /opt/airflow/zetsubou-venv